Fix envvar() function to error if env var doesn't exist

dsc_lib/src/functions/envvar.rs

@@ -25,7 +25,30 @@ impl Function for Envvar {
     }
 
     fn invoke(&self, args: &[Value], _context: &Context) -> Result<Value, DscError> {
-        let val = env::var(args[0].as_str().unwrap_or_default()).unwrap_or_default();
-        Ok(Value::String(val))
+        if let Ok(val) = env::var(args[0].as_str().unwrap_or_default()) {
+            return Ok(Value::String(val));
+        }
+
+        Err(DscError::Function("envvar".to_string(), "Environment variable not found".to_string()))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::configure::context::Context;
+    use crate::parser::Statement;
+
+    #[test]
+    fn valid() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[envvar('PATH')]", &Context::new()).unwrap();
+        assert_eq!(result, std::env::var("PATH").unwrap());
+    }
+
+    #[test]
+    fn invalid() {
+        let mut parser = Statement::new().unwrap();
+        let result = parser.parse_and_execute("[envvar('INVALID')]", &Context::new());
+        assert!(result.is_err());
     }
 }

powershell-adapter/Tests/powershellgroup.config.tests.ps1

@@ -120,7 +120,7 @@ Describe 'PowerShell adapter resource tests' {
         $res.results[0].result.actualState.Prop1 | Should -Be $TestDrive
     }
 
-    It 'DSCConfigRoot macro is empty when config is piped from stdin' -Skip:(!$IsWindows){
+    It 'DSC_CONFIG_ROOT env var does not exist when config is piped from stdin' -Skip:(!$IsWindows){
 
         $yaml = @"
             `$schema: https://raw.githubusercontent.com/PowerShell/DSC/main/schemas/2023/10/config/document.json
@@ -134,10 +134,7 @@ Describe 'PowerShell adapter resource tests' {
                   properties:
                     Name: "[envvar('DSC_CONFIG_ROOT')]"
 "@
-        $out = $yaml | dsc config get
-        $LASTEXITCODE | Should -Be 0
-        $res = $out | ConvertFrom-Json
-        $res.results[0].result.actualState.Name | Should -Be ""
-        $res.results[0].result.actualState.Prop1 | Should -Be ""
+        $null = $yaml | dsc config get
+        $LASTEXITCODE | Should -Be 2
     }
 }